Study looks at Antarctic sea ice changes since the early 20th century, increases since 1979

Posted: January 11, 2022 by oldbrew in climate, data, History, Natural Variation, research, satellites, sea ice, weather
Tags:

Antarctica


The article says ‘The satellite measurements start in 1979’, but the USGS Landsat satellite project has been ‘imaging the Earth since 1972’. The researchers say in the abstract of their paper: ‘In stark contrast to the Arctic, there have been statistically significant positive trends in total Antarctic sea ice extent since 1979. However, the short and highly variable nature of observed Antarctic sea ice extent limits the ability to fully understand the historical context of these recent changes.’ The UK Met Office reported in October 2021: ‘Antarctic sea ice reached a maximum extent (to date) of 18.75 million sq km on 1st September 2021 (Figure 7), which is very close to the 1981-2010 average maximum extent of 18.70 million sq km.’
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A study led by Ohio University researchers shows that the increase of sea ice surrounding Antarctica since 1979 is a unique feature of Antarctic climate since 1905—an observation that paints a dramatic first-ever picture for weather and climate implications on the world’s southernmost continent, says Phys.org.

Dr. Ryan Fogt’s study, published today in Nature Climate Change, is the first to detail sea ice extent surrounding the entire continent though all four seasons over the last century.

Weather, especially winds and temperatures, contribute to sea ice changes. Fogt is professor of Geography in OHIO’s College of Arts and Sciences.

Previous historical estimates of Antarctic sea ice before satellite measurements began around 1979 were obtained mostly through the lens of a small number of weather stations across the vast continent, human observation along the ice edges, and ice core and ocean sediment samples.

However, these estimates all have limitations—most were only observing sea ice conditions in a small area or at a specific time of the year.

But the OHIO study extends the reliable measurements from satellite imagery since 1979 back through the 20th century using historical weather data at places away from the Antarctic continent.

At the heart of Fogt’s statistical reconstruction model is the strong connection Antarctic sea ice shares with regional and large-scale climate variability, captured through a network of 30 long-term temperature and pressure observations across the Southern Hemisphere.

This new study has nearly tripled the length of observed data about the entire continent, instead of just a specific region, and provides a year-round look, rather than an annual average.

“This reconstruction of Antarctic sea ice back through the 20th century gives us detail not only for every season, but also for different regions around the whole of Antarctica. When we sum it up, it gives us the first complete estimate of total Antarctic sea ice extent—how far away the sea ice reaches from the continent—back through the 20th century,” Fogt said.

Regime Shift: Sea increases since 1979, and sudden declines

From the new data, the most impressive feature is what Fogt calls a regime shift. “The short period provided from satellite measurements of Antarctic sea ice is really unique. It’s the only period since the beginning of the 20th century where we see increases in total sea ice in all seasons,” Fogt said.

“We have a statistically significant positive trend over that satellite period. Perhaps even more impressively, these increases since 1979 are juxtaposed by long-term decreases in Antarctic sea ice throughout the early and middle 20th century.”

Ice core records similarly confirm regional aspects of the decrease in much of the 20th century.

Full article here.

Comments
  1. oldbrew says:

    NASA animation: ‘These image pairs show the average concentration of Antarctic sea ice for the month of September (left) and the following February (right) from September 1990 to February 2021.’

    https://earthobservatory.nasa.gov/world-of-change/sea-ice-antarctic

  2. Philip Mulholland says:

    So if the northern hemisphere polar region gets darker (less summer ice) the southern hemisphere polar region gets lighter (more summer sea ice).

  3. cognog2 says:

    What puzzles me here is that the term ‘Antarctica’ ignores the obvious fact that West Antarctica has a very different behaviour to that of the East, due to the presence of the active tectonic rift beneath it. You only have to look at the map of the Pole to see that.
    So; why do the scientists lump the two together; as appears in this article.?

  4. […] Study looks at Antarctic sea ice changes since the early 20th century, increases since 1979 […]

  5. ilma630 says:

    Also some oink from Cambridge University on BBCR4 this morning pontificating about shipping going to the Antarctic spreading non-native organisms. All “coulds”, “mights” and “we don’t knows”! R4 presenter described Antarctic as a “very fragile environment”. Really??!!

  6. *’In stark contrast to the Arctic, there have been statistically significant positive trends in total Antarctic sea ice extent since 1979. However, the short and highly variable nature of observed Antarctic sea ice extent limits the ability to fully understand the historical context of these recent changes.’ *

    Are these, “so-called climate scientists total idiots?”

    SEA ICE PREVENTS SNOWFALL ON THE LAND THAT REBUILDS THE SEQUESTERED ICE ON LAND.

    Alternating warm and cold times are necessary for the polar ice cycles. Warm times build the sequestered ice and then land ice pushed into the ocean currents keep the climate colder until the ice runs out. God, Nature, Whoever or Whatever Planned and/or Designed this Climate System was really Genius. It is self correcting, it snows more in warmest times until more ice causes the climate system to get colder, that forms sea ice that prevents snowfall until the ice is depleted. Yes, it really is this simple, this part of alternating warm and cold periods that show up in ice core records are this simple. There is always more ice accumulation in warm times and every warm time is followed by a colder time with much less ice accumulation and every cold time is followed by a warmer time.

    Alex Pope

    On Tue, Jan 11, 2022 at 3:54 AM Tallbloke’s Talkshop wrote:

    > oldbrew posted: ” The article says ‘The satellite measurements start in > 1979’, but the USGS Landsat satellite project has been ‘imaging the Earth > since 1972’. The researchers say in the abstract of their paper: ‘In stark > contrast to the Arctic, there have been statistica” >

  7. oldbrew says:

    AP: every warm time is followed by a colder time with much less ice accumulation and every cold time is followed by a warmer time.

    In terms of sea ice trends, the two poles seem to behave in opposite ways at least some of the time?

  8. Gamecock says:

    ‘In stark contrast to the Arctic, there have been statistically significant positive trends in total Antarctic sea ice extent since 1979.’

    Well that sorta blows up the whole damn paper. Scientists can study the history of ice around Antarctica. People who consider more ice to be positive are not scientists. The “scientists” publicly declare their bias.

    ‘At the heart of Fogt’s statistical reconstruction model is the strong connection Antarctic sea ice shares with regional and large-scale climate variability’

    Climate doesn’t have variability. Weather has variability. I assure you Antarctica’s climate hasn’t changed a bit in a hundred years. Many thousands of years.

    ‘captured through a network of 30 long-term temperature and pressure observations across the Southern Hemisphere’

    Cirrusly? We know the history of sea ice around Antarctica based on weather reports from Buenos Aires?

    “We don’t have any actual weather stations, so we’ll use Cape Town, Hobart and Stanley.”

    Settlements on Antarctica didn’t begin until the mid-1940s. There weren’t many until the 1960s.

    This is the second study I’ve seen reported in the last month that gleefully fabricates data from irrelevant sources. From at least 1905-1945, we have no clue as to sea ice extent around Antarctica’s 10,000 miles of coast line. Probably not much between 1945-1972, as people sailing around Antarctica would have had no reason to make detailed notes on sea ice. Interest in sea ice extent is a recent fad.

    Sea ice extent before the satellite era is just gross speculation.

  9. JB says:

    @ Gamecock; Thank you. Statistical finagling can be engaged in ad infinitum. But it is worthless if it can’t be proven by direct observation, and fussing with the weather patterns to produce the claimed effect is mere smoke.

  10. Paul Vaughan says:

    2022 a regime shift in seasonal total antarctic sea ice extent in the 20th century (pdf)

    graphs at bottom (p.21 downwards)

  11. Paul Vaughan says:

    some of their pictures

  12. Paul Vaughan says:

    given the pattern gotta wonder if they’ll blame trump

  13. oldbrew says:

    Study abstract: Attributing Antarctic sea ice trends is complicated by the fact that most coupled climate models show negative trends in sea ice extent since 1979, opposite of that observed.

    Models opposite to observations for 40+ years. Where are the shouty headlines? 😆

  14. Paul Vaughan says:

    poll lure op
    pose IT

    if i tell you what you wanna hear…” — ‘mother mother’ TB

    “$leap well at˚Knight” PR f(IT$) sea weather buy don reel US state

  15. oldmanK says:

    From google “To estimate ice area, scientists calculate the percentage of sea ice in each pixel, multiply by the pixel area, and total the amounts. To estimate ice extent, scientists set a threshold percentage, and count every pixel meeting or exceeding that threshold as “ice-covered.” The common threshold is 15 percent.”

    An iceberg covers a certain area; a crushed iceberg covers more. Same ice more coverage; ????

  16. Phil Salmon says:

    Antarctic deep water formation speeds up:

    These two papers indicate that in the last decade or so, formation of highly saline cold deep water formation around the margin of Antarctica has increased and strengthened. In the long term more cold deep water supply from Antarctica will result in a cooling effect on global climate. Antarctica is the biggest global source of cold saline bottom water which drives the Thermo Haline Circulation.

    https://www.nature.com/articles/s41598-020-71290-6

    https://www.science.org/doi/10.1126/sciadv.aav2516

  17. […] Study looks at Antarctic sea ice changes since the early 20th century, increases since 1979 […]

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